File:Twilight description full day.svg|thumb|300px|Dusk is the period of time at the end of evening twilight.
'''Dusk''' is the darkest stage of twilight
in the evening
[''The Random House College Dictionary'', "dusk".]
Pre-dusk, during early to intermediate stages of twilight, there may be enough light in the sky under clear-sky conditions to read outdoors without artificial illumination, but at the end of Twilight#Civil twilight|civil twilight
, when the earth rotates to a point at which the center of the sun
is at 6° below the local horizon, artificial illumination is required to read outside.
[U.S. Naval Observatory. [http://aa.usno.navy.mil/faq/docs/RST_defs.php Rise, Set, and Twilight Definitions].]